Pump



SEAC

SR Cg EFEENCE KR 5 88q4 FIFEESQZ May 7, 1963 E. H. w. SCHMIDT PUMP FiledAug. 11, 1958 ates Uite The present invention relates to pumps.

More particularly, the present invention relates to a pump as well as toa pumping method for moving conductive liquids, particularly liquidmetals, with help of a magnetic field and a direct current traversingthe liquid substantially perpendicularly to each other and to thedirection of the flow of the liquid.

The simplest way of doing this is to use a constant magnetic field and adirect current. For this purpose, low-voltage and high-amperage currentis necessary, and to this end specially constructed machinery isrequired, such as DC. generators or arrangements in which A.C. orthree-phase is applied together with a synchronized magnetic field ofthe same frequency.

Such electrodynamic pumps are used especially for pumping liquid metalsneeded for cooling as well as for transporting heat in nuclear reactors.As these pumps and the liquids transported thereby usually becomeradioactive under the influence of the radiation of the reactor, theyare not accessible for a long period of time. Therefore, the reliabilityof the entire installation must be very high, and this, in turn,requires expensive machinery. Further difficulties arise when liquidsodium or liquid po tassium is to be handled.

It is, therefore, an object of the present invention to overcome theabove disadvantage, and, with this object in view, the present inventionconsists mainly in a method and apparatus for pumping conductiveliquids, especially liquid metals, in which the direct current isproduced thermoelectrically. To this end, two thermocouple elements ofdifferent thermoelectrical properties are brought into good electriccontact at one of their ends, whereas their free ends are electricallyconnected by the liquid to be transported. If the liquid has atemperature different from that of the junction of the thermocoupleelements, a direct current of suflicient amperage is produced to movethe liquid metal under the influence of the electric field.

The invention will be better understood by the following detaileddescription thereof, when read in conjunction with the accompanyingdrawing in which:

FIGS. 1 to 4 show four embodiments of a pump according to the presentinvention.

FIG. illustrates a specific conduit structure usable in connection withpumps according to the present invention.

Referring now to the drawing, and to FIG. 1 thereof in particular, thereis shown a pump which includes a duct or conduit means 1 which ispreferably of substantially rectangular cross-section, through whichconduit means the conductive liquid is to be transported in thedirection of arrows 14. The conduit means are made of a metal of lowelectric conductivity, such as constantan, and are arranged between thespaced. poles 2 and 3 of a suitable magnet means, which derives itsenergy from a source other than the direct current produced by thethermoelectric means described below, in such a way that the lines ofmagnetic flux of the magnetic field generated by the magnet means passthrough the conduit means in a direction substantially perpendicular tothe direction of flow of the liquid.

According to the present invention, the current through the conduitmeans are produced by thermoelectric means, and the latter include twothermocouple elements 5 and 6.

The element 5, which is in the form of a substantially flat plate, isalso made of constantan, and is at one of its ends soldered or otherwiseelectrically connected to the conduit means 1 at one of its narrow sides4. The other element 6, which is made of copper, is soldered to theother end of the element 5 as indicated at 7. This element 6 is in theform of a yoke or stirrup which is insulated from the element 5 andconduit means 1 by a thin layer of air 15, and passes through themagnetic field to the opposite narrow side 8 of the conduit means 1.Thus, the liquid in the conduit means 1 closes the electric circuitbetween the thermoelements 5 and 6. It is true, of course, that sincethe conduit means 1 are made of metal, some of the electric current willflow through the wide side walls. This amount, however, is relativelysmall in comparison to the current flowing through the liquid which isnot only usually a better conductor of electricity than constantan, butwhich also otfers a substantially greater cross-section to the currentflow than do the wide side walls of the conduit means 1. Yet, even thisslight inefficiency may be avoided by making the conduit means ofinsulating material, such as a ceramic material of sufficient heatresistance, in which case suitable means are provided for placing thethermocouple elements 5 and 6 in electrical connection with the liquidin the conduit means. This may be accomplished by introducing leads intothe interior of the conduit means through openings or recesses.Alternatively, a metallic conductor may be diffused into the narrowwalls of the conduit means, in a manner well known in the art.

Such a conduit means 1 is shown in FIG. 5. It is made of electricallyinsulating material with the exception of two places 18 and 19 shaded inthe figure, on opposite sides of the conduit means, where thethermoelectrical current enters and leaves the liquid metal. In theseareas the wall is made electrically conducting for instance by replacingthe insulating material of the wall by a sheet of metal or by any othermeans. If the conduit means is made of ceramic material, it can be madeelectrically conducting by adding metallic powder to the ceramicmaterial before burning. To these electrically conducting parts the twometals of the thermocouple have to be joined conventionally for instanceby soldering.

If a sufficiently great difference in temperature is produced betweenthe connections 7 and 8, then a thermoelectric current will flow throughthe liquid and cause the latter to move in the direction of the arrows14. Suitable means, therefore, are provided for maintaining the junctionof the elements 5 and 6 at a temperature different from that of theliquid flowing through the conduit means. In the embodiment shown inFIG. 1, the temperature is maintained lower by circulating a coolant,such as water, through a cooling conduit 16 which is in good heatexchange relation with the juncture 7 of the elements 5 and 6.

FIG. 2 shows a pump similar to that of FIG. 1 except that thethermocouple element 6 has an additional yoke portion 6, and the twoyoke portions are arranged symmetrically with respect to the conduitmeans 1 in that they pass through the magnetic field above and below theconduit means. While this arrangement increases the distance between themagnetic poles 2 and 3 and consequently reduces the magnetic inductionin the liquid to a certain extent, the magnetic field generated by thethermoelectric current is compensated.

The arrangement according to FIG. 2 further differs from that shown inFIG. 1 in that insulating sheets 9 are interposed between the yokeportions 6, 6' and the element 5 and the conduit means 1, and thatinstead of a cooling means, a heating means, for instance, in the formof a hot liquid in duct 17, is provided for maintaining the junction 7of the thermocouple elements at a temperature higher than that of theliquid in duct 1.

FIG. 3 shows an embodiment of a pump according to the present inventionin which high efiiciency is obtained by avoiding loss of magneticinduction due to relatively great separation of the poles 2 and 3. Thisis achieved by passing one of the .thermocouple elements directlythrough the poles of the magnet means. Thus, the element is constitutedby a number of separate portions 11 which pass through a correspondingnumber of openings 10, 10 of the upper pole 2. In the illustratedembodiment, the openings 10 are in the form of slots and the opening 10"is in the form of a cut-out. Alternatively, the thermocouple element mayconsist of a single yoke, as in the case of FIG. 1, and the pole may beformed with a single slit or cut-out sufficiently large to permit theyoke to pass therethrough.

FIG. 4 illustrates another embodiment of the present invention whereinthe poles 2 and 3 are as near to each other as possible. Thisconstruction is made possible by fashioning one of the thermocoupleelements as a yoke which comprises end portions 12, 12a and bridgeportions 13 which straddle the pole 2. As may readily be seen from thedrawing, the end portion 12 is in contact with the thermocouple elementat 7, whereas the end portion 12a is in contact with the conduitmeans 1. In this way, as in the case of the arrangement shown in FIG. 3,the gap between the poles 2 and 3 need be no greater than the thicknessof the conduit means 1.

The drawings may represent the pump according to the invention innatural size (scale 1:1). However, the dimensions may also besubstantially smaller or bigger.

The Voltage of the thermoelectric current depends upon the material ofthe thermocouple, for which the combination constantan, copper is onlyan example. Using a liquid metal, such as mercury, of about 500 C. and acoolant of 30 C., the voltage produced by a constantan, copperthermoelernent, may be of the order of magnitude of to 20 millivolt.

The amperage produced by this voltage depends essentially upon thedimensions of the whole circuit and the specific resistances of itscomponents. It may be of the order of magnitude of some 20 up to severalthousands of amperes if the strength of the magnetic field is in theorder of magnitude of 1020,000 gauss.

The speed of the liquid depends upon the resistance of the conduit meanswhich it has to pass on its way. In practical embodiments it may be ofthe order of magnitude of some centimeters up to some meters per second.

It will be understood that the present invention is susceptible tomodification in order to adapt it to difierent usages and conditions,and, accordingly, it is desired to comprehend such modifications withinthis invention as may fall within the scope of the appended claims.

What I claim is:

1. A pump for pumping electrically conducting liquids, especially liquidmetals, comprising, in combination, conduit means through which theliquid having a temperature diflerent than an ambient temperature mayflow; a first thermoelectric element; a second thermoelectric element,dissimilar from said first one, said two elements being connected tosaid conduit means and forming a first junction which includes saidliquid as electrical connection in between, said two elements beingfurther connected remote from said first junction so as to form a secondjunction in heat conductive relationship with said ambient temperature,said two elements constituting thermoelectric means for passing a directcurrent through the liquid in said conduit means at said first junctionin a direction substantially perpendicular to said conduit means; andmagnet means for generating a magnetic field the magnetic lines of fluxof which pass through said conduit means in a direction substantiallyperpendicular thereto as well as substantially perpendicular to thedirection in which said direct current is passed through said conduitmeans, said magnet means deriving its energy from a source other thanthe direct current produced by said thermoelectric means.

2. A pump as defined in claim 1 wherein said thermoelectric meansfurther include means for maintaining the junction of said elements at atemperature different from that of the liquid flowing through saidconduit means.

3. A pump as defined in claim 1 wherein said thermoelectric meansfurther include means for maintaining the junction of said elements at atemperature higher than that of the liquid flowing through said conduitmeans. i 4. A pump as defined in claim 1 wherein said thermoelectricmeans further include means for maintaining the junction of saidelements at a temperature lower than that of the liquid flowing throughsaid conduit means.

5. A pump as defined in claim 1 wherein said conduit means are made ofthe same material as one of said thermocouple elements.

6. A pump as defined in claim 1 wherein said conduit means are made ofinsulating material and wherein means are provided placing saidthermocouple elements in electrical connection with the liquid in saidconduit means.

7. A pump as defined in claim 1 wherein said conduit means are ofsubstantially rectangular cross-section.

8. A pump as defined in claim 1 wherein said magnet means comprise twospaced poles between which said conduit means extend.

9. A pump as defined in claim 8 wherein one of said thermocoupleelements extends between said poles of said magnet means.

10. A pump as defined in claim 8 wherein one of said thermocoupleelements extends between said poles of said magnet means and is arrangedsymmetrically with respect to said conduit means.

11. A pump as defined in claim 8 wherein one of said thermocoupleelements passes through said magnet means.

12. A pump as defined in claim 8 wherein one of said thermocoupleelements comprises bridge portions straddling said magnet means.

13. A pump as defined in claim 1 wherein one of said thermocoupleelements is in the form of substantially fiat plate.

References Cited in the file of this patent UNITED STATES PATENTS330,451 Weston Nov. 17, 1885 2,031,967 Mathias Feb. 25, 1936 2,686,474Pulley Aug. 17, 1954 2,715,686 Asti Aug. 16, 1955 2,748,710 VandenbergJune 5, 1956 2,798,434 Brill et al. July 9, 1957 2,919,356 Fry Dec. 29,1959 2,962,718 Hilgert Nov. 29, 1960 2,977,050 Sparrow Mar. 28, 1961

1. A PUMP FOR PUMPING ELECTRICALLY CONDUCTING LIQUIDS, ESPECIALLY LIQUIDMETALS, COMPRISING, IN COMBINATION, CONDUIT MEANS THROUGH WHICH THELIQUID HAVING A TEMPERATURE DIFFERENT THAN AN AMBIENT TEMPERATURE MAYFLOW; A FIRST THERMOELECTRIC ELEMENT; A SECOND THERMOELECTRIC ELEMENT,DISSIMILIAR FROM SAID FIRST ONE, SAID TWO ELEMENTS BEING CONNECTED TOSAID CONDUIT MEANS FORMING A FIRST JUNCTION WHICH INCLUDES SAID LIQUIDAS ELECTRICAL CONNECTION IN BETWEEN, SAID TWO ELEMENTS BEING FURTHERCONNECTED REMOTE FROM SAID FIRST JUNCTION SO AS TO FORM A SECONDJUNCTION IN HEAT CONDUCTIVE RELATIONSHIP WITH SAID AMBIENT TEMPERATURE,SAID TWO ELEMENTS CONSTITUTING THERMOELECTRIC MEANS FOR PASSING A DIRECTCURRENT THROUGH THE LIQUID IN SAID CONDUIT MEANS AT SAID FIRST JUNCTIONIN A DIRECTION SUBSTANTIALLY PERPENDICULAR TO SAID CONDUIT MEANS; ANDMAGNET MEANS FOR GENERATING A MAGNETIC FIELD THE MAGNETIC LINES OF FLUXOF WHICH PASS THROUGH SAID CONDUIT MEANS IN DIRECTION SUBSTANTIALLYPERPENDICULAR THERETO AS WELL AS SUBSTANTIALLY PEREPNDICULAR TO THEDIRECTION IN WHICH SAID DIRECT CURRENT IS PASSED THROUGH SAID CONDUITMEANS, SAID MAGNET MEANS DERIVING ITS ENERGY FROM A SOURCE OTHER THANTHE DIRECT CURRENT PRODUCED BY SAID THERMOELECTRIC MEANS.